Although the overall rheumatoid arthritis-related mortality rates have been decreasing in recent years, rates of mortality among patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD) remain stable, except for in patients aged 65 to 84 years, for whom outcomes have improved, according to findings published in the Annals of the American Thoracic Society.
The burden of RA and RA-ILD has not been well-characterized in recent years. Therefore, researchers sought to remedy this by describing RA and RA-ILD-related mortality trends and rates from 2005 to 2018, in the United States, stratified by demographics. Data were found through the Centers for Disease Control and Prevention’s Multiple Cause of Death Database, which includes data on all deceased US residents and identifies RA and RA-ILD-related deaths by International Classification of Diseases, Tenth Edition (ICD-10) codes. Of the 36,067,309 deaths that occurred during the stated time frame, 0.34% (n=123,012) had RA, and, of those, 9.9% (n=12,180) also had ILD (13.3% of men and 8.7% of women). The underlying cause of death (UCD) was coded as either ILD or RA in 77.4% of patients with RA-ILD, and RA was the UCD in 25.6% of patients with RA alone.
Both RA and RA-ILD-related mortality rates were higher among women and older age groups. However, ILD prevalence was higher among men with RA than women with RA (13.3% vs 8.7%). Mortality rates were highest among Native American patients, followed by White patients. The lowest mortality rate was seen in Asian patients, followed by Black patients. Although Hispanic patients had lower RA-related rates of mortality than White patients, they had higher RA-ILD-related rates. Otherwise, the trends were similar.
The overall rate of RA-related mortality per 1,000,000 population decreased from 30.6 in 2005 to 22.2 in 2018, with regression analysis showing a negative temporal trend (P <.001). In men, the age-adjusted RA-related mortality per 1,000,000 decreased from 19.6 in 2005 to 13.8 in 2018 (P <.001), while in women, it decreased from 38.0 to 28.3 (P <.001), which equated to a decrease of 29.6% in the overall mortality rate for men and 25.6% for women. RA-related mortality decreased significantly in all age groups: 45 to 54 years (7.0 in 2005 to 5.6 in 2018; P =.02), 55 to 64 years (26.4 in 2005 to 21.1 in 2018; P <.001), 65 to 74 years (103.3 in 2005 to 65.7 in 2018; P <.001), 75 to 84 years (279.5 in 2005 to 194.2 in 2018; P <.001), and 85 years and older (495.0 in 2005 to 403.7 in 2018; P <.001).
The primary study limitation was the necessity of relying on practitioners to accurately identify and code RA and RA-ILD.
“Further studies are warranted to investigate the role of genetics and environmental factors contributing to these differences,” wrote the study authors. “Our findings could facilitate the design of these future studies and also enable appropriate representation in clinical trials of demographic groups that are more significantly affected by this condition.”
Jeganathan N, Nguyen E, Sathananthan M. Rheumatoid arthritis and associated-interstitial lung disease: mortality rates and trends. Ann Am Thorac Soc. Published online May 5, 2021. doi:10.1513/AnnalsATS.202102-115OC